Pressure-sensitive recording materials utilizing a coloring reaction of a color former and a developer such as clay materials (e.g., acid clay, active clay, attapulgite, zeolite, bentonite, kaolin, etc.), metal salts of aromatic carboxylic acids, phenol-formaldehyde resins, etc., are well known as described, for example, in U.S. Pat. Nos. 2,505,470, 2,505,489, 2,550,471, 2,548,366, 2,712,507, 2,730,456, 2,730,457, and 3,418,250, Japanese Patent Application (OPI) Nos. 28411/74 and 44009/75, (the term "OPI" as used herein refers to a "published unexamined Japanese patent application"), etc.
In these developers, metal salts of aromatic carboxylic acids are excellent in light resistance, moisture resistance, solvent resistance, etc., of the colored materials formed, and are widely used at present.
However, even in the case of using metal salts of aromatic carboxylic acids as a developer, the light resistance and plasticizer resistance of colored materials formed are not yet fully satisfactory. The plasticizer resistance used herein refers to a property capable of preventing the disappearance of the colored images after placing a sheet containing the plasticizer.